British investigators said "there is no evidence" that lithium-ion batteries caused the fire that damaged a parked Ethiopian AirlinesBoeing 787 at London's Heathrow International Airport on Friday, but they didn't indicate what may have sparked the flames.

In a four-paragraph release Saturday, the U.K. Air Accidents Investigation Branch said the fire, which broke out when nobody was aboard, caused "extensive heat damage in the upper portion of the rear fuselage" and spread smoke throughout the fuselage...